Rolling door drive assemblies are well known and typically have a chassis which supports a motor with an associated drive (eg. a gear). The chassis is usually connected to a final drive unit (eg. a gear drum having internal teeth) which meshes with the drive. The final drive unit is connected to the rolling door to cause it to move up or down by operation of the motor.
The rolling door is held in position by end supports at both ends which engage a mounting axle passing axially through the rolling door. The rolling door drive assembly is mounted on the axle at one end between the end of the door and the adjacent end support for the axle.
A typical example of such rolling door assemblies is disclosed in Australian Patent number 558906. These assemblies are predominantly mechanical and require regular servicing. To achieve this it is necessary to either remove or at least disengage the rolling door from the axle support. Accordingly there has been a well defined need to develop assemblies which may be readily accessible or easily removed from the door.
A similar need has been defined in the retrofit market in which the assembly is totally replaced by a new or reconditioned assembly.
Likewise as the door opening is usually situated very close to defining side walls of a shed or garage there has been a need to have slim line assemblies which may be fitted between the opening and those walls.
One prior attempt to meet one or more of these needs is the drive assembly disclosed in Australian Patent number 601414. This relates to the general type of assembly which has a chassis and a final drive unit rotatably mounted to the chassis about an axis of rotation for driving connection to a door for rolling the door about a door mounting axle. The assembly has a motor fixed relative to the chassis which can drive the final drive unit.
More particularly this prior assembly has a housing for a part of the drive assembly which has a recessed channel adapted to receive a mounting bracket. In this way the mounting bracket connection to the assembly occurs in the recess which minimises the width of the installed assembly. The housing assembly of this is a complicated design which must be specially manufactured. Whilst it does allow the assembly to fit very closely against the mounting bracket, it still does not facilitate easy servicing. To remove the housing the assembly must be first disengaged from the door axle which is a difficult and time consuming job, especially where space between the assembly and the side wall is restricted.
Even if the space is not restricted the housing cannot be disengaged from the assembly without movement of the entire assembly. This means that the access for servicing is still restricted. As shown in the drawings of this patent, the motor is located in the housing above the axis of rotation. This further causes the maintenance to be complicated as the motor is virtually on the extreme of the area to be reached by a technician.
This patent also discloses a clutch interposed in the drive train which permits the fixed motor to be engaged and disengaged. An exterior handle directly connects to and operates the clutch so that when the drive train is engaged the motor will drive the rolling or unrolling of the door. The clutch would normally only be used when manual operation of the door is desired. In this instance the motor is disengaged. To re-engage the motor the clutch is used to manually engage the drive train.
A further example of an assembly of this type is Australian Patent number 519424. In this assembly the motor is also located at the upper extremity of the assembly, making maintenance difficult. In this patent, the motor is mounted on a frame which allows it to be disengaged from the drive train. The handle removes the pawl from the teeth and the motor can drop down. To re-engage the motor, it needs to be manually lifted and the pawl reengaged in the teeth.
Another approach is disclosed in an assembly sold under the trade marks Merlin and Parker in Australia. This assembly has an externally toothed final drive unit which is attached to a chassis. The chassis has a hub which can be located on a door mounting axle and an arm extending down from the hub. The arm is removably connected via two vertically orientated bolts and a horizontal location bolt, to a lower support which carries a motor and circuitry etc. To remove the support from the arm, the location bolt needs to be loosened and the vertical bolts removed. The disengaging movement is initially traverse to the door mounting axle to clear the location bolt and then downward.
It is thought that this assembly, by requiring transverse movement, restricts its application in confined areas as such movement may contact an adjacent wall. Also, as the connection between the support and the hub is spaced by an arm, a twisting moment is imposed upon the arm and hence the hub, when the motor on the support is operated to rotate the final drive unit. Accordingly, the arm needs significant reinforcement to compensate for this twisting moment.